12 HORTICULTURAL MANUAL. 



surface is covered at once with evergreen leaves or othei 

 light shading to lessen evaporation, which is mainly re- 

 moved when the plants begin to appear. The after-care of 

 the seedlings is given in the chapter on seedling-growth. 



FIG. 3. Lath -covered Shed for Seed-beds. (After Bailey.) 



14. Retained Vitality of Seeds. Varied opinions have 

 been given as to the duration of vitality of seeds of the 

 cultivated plants. This largely comes from the varied 

 modes of drying and storing of seeds. As an instance, 

 onion and other seeds are often sunk in water to clean, as 

 the chaff rises to the surface. Such seed is only good for 

 one year as a rule. But onion-seed properly handled is 

 good for ten years or more. As a rale, the vitality of all 

 seed is reduced by age. Some seeds with the best care 

 rarely germinate when more than one year old, and the 

 fruit-tree seeds kept dry for one year are much lowered in 

 vitality. Tables are often compiled giving the extreme 

 duration of seeds under proper conditions. But they are 

 so unsafe, on account of varying conditions, that the cer- 

 tain rule is to plant seeds the season following their gather- 

 ing. The only exceptions are possibly with melons, cu- 

 cumbers, squashes, and some other plants noted for exces- 

 sive vigor of growth. It is claimed in such cases that seed 

 three or four years old gives less growth and more fruit 

 than the new seed. 



